Julia Zelixon stood at the center of a scrum of white-coated doctors, blue stethoscope around her neck, taking notes and fielding questions about Phyllis, her patient.

The slender white-haired woman suffered from inoperable bladder cancer, and her breathing had become so labored that the doctors feared she would need a mechanical ventilator. Julia had a suggestion: decrease the fluids in Phyllis's system to give her lungs more room to expand.

''What are your goals on i's and o's?" she then asked confidently, using nurse shorthand for the patient's IV fluid ''input" and urine ''output."

While Julia, a first-year nurse in the surgical intensive care unit at Massachusetts General Hospital, consulted on the case, her teacher sat in the hall, drinking coffee and talking about taking her two children to see ''The Lion King" during school vacation. There wasn't much for M.J. Pender to do, and that was as it should be.

For today, if nothing went wrong, was to be the last day of Julia's eight-month apprenticeship -- a crash course in the most challenging brand of nursing at a hospital that cares for some of New England's sickest patients. M.J. had deliberately skipped the beginning of morning rounds to give her student more independence.

Julia, she said, ''is definitely ready to be on her own, especially for this kind of assignment."